In the use of textbooks to learn the subject matter of a specific field of knowledge, students often find that they need additional help to understand the material that is presented in the textbooks.
For example, textbooks currently available will usually explain a given principle in a few pages written by a professional who has an insight in the subject matter that is not shared by students. The explanations are often written in an abstract manner which leaves the students confused as to the application of the principles. The explanations given are not sufficiently detailed and extensive to make the student aware of the wide range of applications and different aspects of the principle being studied. The numerous possible variations of principles and their applications are usually not discussed, and it is left for the students to discover these for themselves while doing exercises. Accordingly, the average student is expected to rediscover that which has been long known and practiced, but not published or explained extensively.
In textbooks the examples usually following the explanation of a topic are too few in number and too simple to enable the student to obtain a thorough grasp of the principles involved. The explanations do not provide sufficient basis to enable a student to solve problems that may be subsequently assigned for homework or given on examinations.
The examples are presented in abbreviated form which leaves out much material between steps, and requires that students derive the omitted material themselves. As a result, students find the examples difficult to understand--contrary to the purpose of the examples.
Examples, are furthermore, often worded in a confusing manner. They do not state the problem and then present the solution. Instead, they pass through a general discussion, never revealing what is to be solved for.
Examples, also, do not always include diagrams/graphs, wherever appropriate, and students do not obtain the training to draw diagrams or graphs to simplify and organize their thinking.
Students can learn the subject only by doing the exercises themselves and reviewing them in class, to obtain experience in applying the principles with their different ramifications.
When reviewing the exercises in classrooms, instructors usually request students to take turns in writing solutions on the boards and explaining them to the class. Students often find it difficult to explain in a manner that holds the interest of the class, and enables the remaining students to follow the material written on the boards. The remaining students seated in the class are, furthermore, too occupied with copying the material from the boards, to listen to the oral explanations and concentrate on the methods of solution.
From the preceding conditions faced by students, it is understandable that students will often require study aids to supplement the class materials, usually in the form of textbooks, in order to help them understand the subject matter to be learned.
Study aids are often in the form of booklets which summarize the essential facts and theorems dealt with in a textbook. Study aids can also be in the form of problem solving books which contain a large number of solved problems dealing with the various topics presented in the textbook. Other study aids are in the form of laminated charts which provide a quick review for summary of the important materials in the textbook.
Heretofore, however, such study aids were usually found at locations quite remote from the textbooks for which the study aids were intended. For example, the textbooks may be stored on one floor of a bookstore, whereas the study aids could be stored on another floor or in the basement of the bookstore building.
As a result, students were often unaware of the availability of study aids that could be used in conjunction with their textbooks to learn the subject matter more effectively.